This is a polished fossil coral colony quarried from near Assa Zag Morocco in the Western Sahara. The genus appears to be Hexagonaria and it would be Devonian in age, 350-400 million years old. The polishing allows for the beautiful, inner structure of the coral colony to be seen. The base of the rock has been cut flat, allowing for it to sit upright on a flat surface for a very aesthetic display.
Hexagonaria is a genus of colonial rugose coral. Fossils are found in rock formations dating to the Devonian period, about 350 million years ago. Fossils of this genus form Petoskey stones, the state stone of Michigan